1 Also see the Khronos landing page for glslang as a reference front end:
3 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
5 The above page includes where to get binaries, and is kept up to date
6 regarding the feature level of glslang.
11 [![Build Status](https://travis-ci.org/KhronosGroup/glslang.svg?branch=master)](https://travis-ci.org/KhronosGroup/glslang)
12 [![Build status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master)
14 An OpenGL and OpenGL ES shader front end and validator.
16 There are several components:
18 1. A GLSL/ESSL front-end for reference validation and translation of GLSL/ESSL into an AST.
20 2. An HLSL front-end for translation of a broad generic HLL into the AST. See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
22 3. A SPIR-V back end for translating the AST to SPIR-V.
24 4. A standalone wrapper, `glslangValidator`, that can be used as a command-line tool for the above.
26 How to add a feature protected by a version/extension/stage/profile: See the
27 comment in `glslang/MachineIndependent/Versions.cpp`.
29 Tasks waiting to be done are documented as GitHub issues.
31 Execution of Standalone Wrapper
32 -------------------------------
34 To use the standalone binary form, execute `glslangValidator`, and it will print
35 a usage statement. Basic operation is to give it a file containing a shader,
36 and it will print out warnings/errors and optionally an AST.
38 The applied stage-specific rules are based on the file extension:
39 * `.vert` for a vertex shader
40 * `.tesc` for a tessellation control shader
41 * `.tese` for a tessellation evaluation shader
42 * `.geom` for a geometry shader
43 * `.frag` for a fragment shader
44 * `.comp` for a compute shader
46 There is also a non-shader extension
47 * `.conf` for a configuration file of limits, see usage statement for example
52 Instead of building manually, you can also download the binaries for your
53 platform directly from the [master-tot release][master-tot-release] on GitHub.
54 Those binaries are automatically uploaded by the buildbots after successful
55 testing and they always reflect the current top of the tree of the master
61 (For MSVS: 2015 is recommended, 2013 is fully supported/tested, and 2010 support is attempted, but not tested.)
62 * [CMake][cmake]: for generating compilation targets.
63 * make: _Linux_, ninja is an alternative, if configured.
64 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
65 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
66 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
70 The following steps assume a Bash shell. On Windows, that could be the Git Bash
71 shell or some other shell of your choosing.
73 #### 1) Check-Out this project
76 cd <parent of where you want glslang to be>
77 git clone https://github.com/KhronosGroup/glslang.git
80 #### 2) Check-Out External Projects
83 cd <the directory glslang was cloned to, "External" will be a subdirectory>
84 git clone https://github.com/google/googletest.git External/googletest
87 If you want to use googletest with Visual Studio 2013, you also need to check out an older version:
90 # to use googletest with Visual Studio 2013
91 cd External/googletest
92 git checkout 440527a61e1c91188195f7de212c63c77e8f0a45
96 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
97 or wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, install
98 spirv-tools with this:
101 ./update_glslang_sources.py
106 Assume the source directory is `$SOURCE_DIR` and the build directory is
107 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
114 For building on Linux:
117 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
118 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
121 For building on Windows:
124 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
125 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
128 The CMake GUI also works for Windows (version 3.4.1 tested).
130 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
131 to prevent the addition of execution permission on files.
133 #### 4) Build and Install
140 cmake --build . --config Release --target install
141 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
144 If using MSVC, after running CMake to configure, use the
145 Configuration Manager to check the `INSTALL` project.
147 ### If you need to change the GLSL grammar
149 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
150 bison if it changes, the output files are committed to the repo to avoid every
151 developer needing to have bison configured to compile the project when grammar
152 changes are quite infrequent. For windows you can get binaries from
153 [GnuWin32][bison-gnu-win32].
155 The command to rebuild is:
158 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
159 bison --defines=MachineIndependent/glslang_tab.cpp.h
160 -t MachineIndependent/glslang.y
161 -o MachineIndependent/glslang_tab.cpp
164 The above commands are also available in the bash script in `updateGrammar`,
165 when executed from the glslang subdirectory of the glslang repository.
166 With no arguments it builds the full grammar, and with a "web" argument,
167 the web grammar subset (see more about the web subset in the next section).
169 ### Building to WASM for the Web and Node
171 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
172 * For building the web subset of core glslang:
173 + execute `updateGrammar web` from the glslang subdirectory
174 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
175 + set `-DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`
176 + turn on `-DENABLE_GLSLANG_WEB=ON`
177 + optionally, for GLSL compilation error messages, turn on `-DENABLE_GLSLANG_WEB_DEVEL=ON`
178 * `emsdk` needs to be present in your executable search path, *PATH* for
179 Bash-like enivironments
180 + [Instructions located
181 here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
182 * Wrap cmake call: `emcmake cmake`
183 * To get a fully minimized build, make sure to use `brotli` to compress the .js
189 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_WEB=ON \
190 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
196 Right now, there are two test harnesses existing in glslang: one is [Google
197 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
198 runs unit tests and single-shader single-threaded integration tests, while
199 the latter runs multiple-shader linking tests and multi-threaded tests.
203 The [`runtests` script](Test/runtests) requires compiled binaries to be
204 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
205 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
206 otherwise, you may want to modify the path in the `runtests` script.
208 Running Google Test-backed tests:
217 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
219 # or, run the test binary directly
220 # (which gives more fine-grained control like filtering):
221 <dir-to-glslangtests-in-build-dir>/glslangtests
224 Running `runtests` script-backed tests:
227 cd $SOURCE_DIR/Test && ./runtests
230 ### Contributing tests
232 Test results should always be included with a pull request that modifies
235 If you are writing unit tests, please use the Google Test framework and
236 place the tests under the `gtests/` directory.
238 Integration tests are placed in the `Test/` directory. It contains test input
239 and a subdirectory `baseResults/` that contains the expected results of the
240 tests. Both the tests and `baseResults/` are under source-code control.
242 Google Test runs those integration tests by reading the test input, compiling
243 them, and then compare against the expected results in `baseResults/`. The
244 integration tests to run via Google Test is registered in various
245 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
246 option `--update-mode`, which, if supplied, will overwrite the golden files
247 under the `baseResults/` directory with real output from that invocation.
248 For more information, please check `gtests/` directory's
249 [README](gtests/README.md).
251 For the `runtests` script, it will generate current results in the
252 `localResults/` directory and `diff` them against the `baseResults/`.
253 When you want to update the tracked test results, they need to be
254 copied from `localResults/` to `baseResults/`. This can be done by
255 the `bump` shell script.
257 You can add your own private list of tests, not tracked publicly, by using
258 `localtestlist` to list non-tracked tests. This is automatically read
259 by `runtests` and included in the `diff` and `bump` process.
261 Programmatic Interfaces
262 -----------------------
264 Another piece of software can programmatically translate shaders to an AST
265 using one of two different interfaces:
266 * A new C++ class-oriented interface, or
267 * The original C functional interface
269 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
271 ### C++ Class Interface (new, preferred)
273 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
274 glslang namespace and contains the following, here with suggested calls
275 for generating SPIR-V:
278 const char* GetEsslVersionString();
279 const char* GetGlslVersionString();
280 bool InitializeProcess();
281 void FinalizeProcess();
285 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
286 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
287 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
289 const char* getInfoLog();
294 const char* getInfoLog();
298 For just validating (not generating code), subsitute these calls:
301 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
302 setEnvClient(EShClientNone, 0);
303 setEnvTarget(EShTargetNone, 0);
306 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
307 details. There is a block comment giving more detail above the calls for
308 `setEnvInput, setEnvClient, and setEnvTarget`.
310 ### C Functional Interface (original)
312 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
313 as the `Sh*()` interface, as all the entry points start `Sh`.
315 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
316 building call back that is passed the AST and can then execute a backend on it.
318 The following is a simplified resulting run-time call stack:
321 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
324 In practice, `ShCompile()` takes shader strings, default version, and
325 warning/error and other options for controlling compilation.
327 Basic Internal Operation
328 ------------------------
330 * Initial lexical analysis is done by the preprocessor in
331 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
332 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
334 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
335 aid of a symbol table and an AST. The symbol table is not passed on to
336 the back-end; the intermediate representation stands on its own.
337 The tree is built by the grammar productions, many of which are
338 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
340 * The intermediate representation is very high-level, and represented
341 as an in-memory tree. This serves to lose no information from the
342 original program, and to have efficient transfer of the result from
343 parsing to the back-end. In the AST, constants are propogated and
344 folded, and a very small amount of dead code is eliminated.
346 To aid linking and reflection, the last top-level branch in the AST
347 lists all global symbols.
349 * The primary algorithm of the back-end compiler is to traverse the
350 tree (high-level intermediate representation), and create an internal
351 object code representation. There is an example of how to do this
352 in `MachineIndependent/intermOut.cpp`.
354 * Reduction of the tree to a linear byte-code style low-level intermediate
355 representation is likely a good way to generate fully optimized code.
357 * There is currently some dead old-style linker-type code still lying around.
359 * Memory pool: parsing uses types derived from C++ `std` types, using a
360 custom allocator that puts them in a memory pool. This makes allocation
361 of individual container/contents just few cycles and deallocation free.
362 This pool is popped after the AST is made and processed.
364 The use is simple: if you are going to call `new`, there are three cases:
366 - the object comes from the pool (its base class has the macro
367 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
369 - it is a `TString`, in which case call `NewPoolTString()`, which gets
370 it from the pool, and there is no corresponding `delete`
372 - the object does not come from the pool, and you have to do normal
373 C++ memory management of what you `new`
376 [cmake]: https://cmake.org/
377 [python]: https://www.python.org/
378 [bison]: https://www.gnu.org/software/bison/
379 [googletest]: https://github.com/google/googletest
380 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
381 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot